Borate-hypochlorite bleach



or w- BORATE-HYPOCHLGRITE BLEACH Stephen E. Stephanou, Santa Ana,Lawrence L. Schwalley, Whittier, and Sam H. Lee, Anaheim, Calif.,assignors to United States Borax & Chemical Corporation, Los Angeles,Calif., a corporation of Nevada No Drawing. Filed July 3, 1959, Ser. No.824,778

' 8Claims. Cl. 252-99 The present invention is a continuation-in-part ofSerial No. 730,541, filed April 24, 1958, which was in turn acontinuation-in-part of Serial No. 709,439, filed January 12, 1958, nowabandoned.

This invention relates to new and novel compositions of matter and hasmore particular reference to boratehypochlorite bleach compositions andmethod for making the same.

It is well known that sodium hypochlorite containing materials have notpreviously attained commercial success as solid bleaches due to theirextreme hygroscopicity and instability. Various methods for themanufacture of sodium hypochlorite in solid form have been describedsuch as by mixing sodium hypochlorite solution with soluble anhydroussalts capable of taking their water of crystallization from thehypochlorite and of solidifying into a crystalline mass. We have found,however, that it is not possible to produce commercially acceptableproducts by these prior art methods since they are not sufiicientlystable.

We have found that when the alkali metal borates are reacted withhypochlorite with precisely controlled (OCl') B 0 and X 0 B 0 ratios, asolid bleach is produced having stability characteristics heretoforeunattained by prior art compositions and methods.

It is therefore the principal object of the present invention to providenew and novel bleach compositions.

A further object of this invention is to provide a method of makingble'ach compositions having stability heretofore unattained by prior artbleach compositions.

A still further object is to provide a method of making theborate-hypochlorite compositions of the present invention.

Other objects will become apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, the inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description setting forth indetail certain illustrative embodiments of the invention, these beingindicative, however, of but a few of the ways in which the principle ofthe invention may be employed.

Broadly stated, the present invention comprises a stableborate-hypochlorite bleach in a solid substantially dry form, saidborate-hypochlorite composition having from 0.029 to 0.36 mole of (OCl-)per mole of B 0 and from 0.30 to 0.90 mole of X 0 per mole of B 0 whereX is at least one material selected from the group consisting of thealkali metals, said X 0 comprising the titratable alkalinity of saidborate-hypochlorite.

From the broadly stated paragraph it will be noted that the products ofthe present invention are defined as having critical (OCl"') B 0 and X 0B 0 mole ratios. We have found that in order for borate-hypochloritecompositions to have low hygroscopicity, high stability and goodbleaching properties, it is absolutely necessary to maintain from 0.029to 0.36 mole of (OCl-) per mole of B 0 and from'0.30 to 0.90 mole of X 0per mole of 2,977,3l4. Patented Mar. 28, 1961 ice B 0 Additionally, inthe manufacture of the present compositions, as explained in thefollowing examples, it will be seen that various soluble crystallinesalts, such as the alkali metal chlorides and chlorates, can be presentas impurities. However, it is to be completely understood that the X20comprises only the titratable alkalinity calculated as X 0 fromhypochlorites and borates. The titratable alkalinity is readilydetermined by potentiometric titration, a technique known to thoseskilled in the art.

Thus, it is again iterated that in order to obtain bleach compositionsof low hygroscopicity and high stability the aforegoing ratios of (001-)B 0 and X 0 B 0 must be observed.

The present process involves the chlorination of an alkali metal borateor the addition of an alkali metal borate to sodium hypochlorite. Thestarting admixture can be prepared in a number of ways. For example,borax and caustic soda; sodium metaborate; potassium metaborate; boraxand boric acid; lithium borate and borax; potassium borate and causticsoda; sodium metaborate and boric acid; boric acid and sodium orpotassium hydroxides and various other combinations of these borates canbe used in the production of the boratehypochlorite compositions of thepresent invention.

Using the above-mentioned borates and combinations thereof the presentcompositions can be prepared in a number of ways. In the preferredembodiment of our invention we first prepare sodium hypochlorite bychlorinating an aqueous solution of sodium hydroxide, make a slurry ofthe hypochlorite solution with a borate or combination of borates andthen rapidly dry the resultant slurry. In this preferred embodiment ofour invention we combine the ingredients in such proportion that thefinished product has from 0.15 to 0.2 mole of (001*) per mole of B 0 andfrom 0.3 to 0.6 mole of Na O per mole of B 0 However, it is to beclearly understood that the present invention is not to be limited bythe particular process used to make the borate-hypochlorite bleach, itonly being important that the final product contains the proper ratio ofingredients and the drying step be completed as rapidly as possible.

The present bleaches can also be prepared by the dry admixing of boraxand caustic soda and then chlorinating the admixture with chlorine gas.Thus the present materials can be prepared by the use of alkali metalhypochlorites or chlorine gas introduced into an aqueous slurry or drypowder. If direct chlorination is used the desired endpoint forchlorination can be achieved by continuous measurement of pH or bychemical analysis. The chlorine or chlorine containing material can alsobe calculated and added in the required total amount.

Also, if desired, more than one kind of alkali metal borate can be usedto produce the present products. Sodium borate and potassium borate canbe simultaneously chlorinated or a sodium borate can be reacted withNaOH and KOH and then chlorinated. However, it must be remembered, thetotal X 0 must remain in the range indicated above.

Any of the well-known methods of drying, such as vacuum oven drying,spray drying, drum drying, forced air drying, etc., can be used as longas such drying can be performed rapidly.

The present compositions may be either in crystalline or amorphous form.In any event rapid drying methods must be used to avoid decompositiondue to overheating.

In the specification and claims the term dry is meant to convey amaterial having no free water. Thus, while our finished compositionscontain varying amounts of chemically combined water or water ofcrystalliza- G17 tion, the material is dry in that there issubstantially no free or chemically uncombined water.

A study of the chemistry involved in making the present products l r ealh t. the n ti m x ure. hetq e chlorie nation will always have a higher X0 B 0 mole ratio than the finished product which comprises from 0.029 to0.36 mole (.OCl) and from 0.30 to 0.9.0 m le X 0 per mole of B 0 bereadily understood since the chlorination produces the formation ofchlorides and chlorates in addition to the desired borate-hypochlorite.While it 'is' entirely true that the total alkali metal at the start ofthe reaction is' also present when the reaction is completed, neverthe zless the fact remains that neutral chlorides and chlorates are formed.This accounts for the final XgQ BQQ}, ratio. being lower than thestarting ratio, sincethe chlorides and chlorates formed are nottitratable alkali;

While as noted above, chlorides and chlorates are formed during theproduction of the borate-hypochlorite, they are not harmful to thefinished product."

The invention will be understood in more detail from the examples whichfollow. The following formulationsare given only in the way of exampleandare. in no. way presented to indicate that the formulations ofcomposi tions of this invention are limited to they cited examples:

Caustic soda (455' grams) was added to 520 grams of water and stirreduntil solution was complete. The stoichiometric amount of chlorine (390grams C1 necessary to react with the NaOH to form NaQQl was. then passedinto the solution. 1450 grams of borazr pent-ahydrate and 625 grams ofboric acid were then slurried into. the sodium hypochlorite solution.

- The slurry was then pi t through a drum dryer. The drum dryercomprised two rolls having 0.010 clearance and an internal steampressure of 60#/sq. in.-this'gave an external roll temperature of 153 C.The rolls were rotated 8 r.p.m. which gave a material contact time of3.85 seconds.

The resultant product was a free-flowing stable solid bleach whichanalyzed about 6.6% available chlorine and had (001") B 0 and Na O B 0mole ratios of 0.151 and 0.458, respectively.

Chemical analysis'of this product was as follows;

B rge Naoci 6.9 Neel 6-9 NaCl0 1.2 Na O' p 14.6 B 0 42.7 H2O 17.7

Using the technique. and equipment of .Example I Percent NaOCl A 7 7 8.9NaCl 16.2 NaClO 1.4 Na O V 13.9. B203 51-: a i l The decrease in X 0content will 4 III- Sodium metaborate (Na B O -4H O) (420 grams) wasadded to 615 mls. of water and the mixture stirred until solution wascomplete at room temperature. 65.5 grams of borax (Na B O .-10H O) werethen added and stirred into the solution. In this case solution of theborax is not complete.

Dry chlorine (72 grams) was passedinto the mixture 7 while stirring(showed a pH of 9.3 upon 1:10 by weight bleach which analyzed 5.5%available chlorine and had ple of the supernatant liquid from the slurryshowed a pH of 9.6-9.8 upon a 1:10 by weight dilution.

The slurry was dried as above and resulted in a freeflowing solid whichanalyzed 5.66% available chlorine and had final (OC1-) B 0 and Na O B 0mole ratios of 0.148 and 0.66, respectively.

Sodium metaborate (Na B O -4H O) (6.788 grams) and potassium metaborate(,K B O -4H O') (821: grams) were s-lurried in. 9390 grams of water. Thetemperature. of the slurry was. maintained at below 26 C. and drychlorine. was passed into the slurry until. the pH of the supernatantliquid was 9.35.

The chlorinated slurry was then dried in a direct gasfiredspray drierhaving an inlet temperature of 400 F.

and an outlet temperature of 243 F.

The resultant product was a free-flowingstable solid bleach whichanalyzed 3.0% available chlorine and final (OCl-) B 0 and Na O B 0 moleratios. of 0.077 and 0.56, respectively.

The available chlorine content of the solid material of the aboveexamples was measured by using the standard potassium iodide-thiosulfatetitration.

1.0 gram of sample was added to l00 mls. of acidified KI solution. Theliberated iodine was titrated with 0.1 N' standard sodium thiosulfatesolution to-theusual endpoint (disappearance of yellow color) Thepercent of available chlorine was calculated as follows:

ml. thiosulfate X 0.1

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

We, therefore, particularly point out and distinctly claim as ourinvention:

1. A composition of matter consisting essentially of a stableborate-hypochlorite bleach in a solid substantially dry form, saidborate-hypochlon'te havingfrom 0.029. to

0.36 mole of"(OCl-) per mole of B 0 and from 0.30 to mole t X201 ma e.BzQn hfi X, v eas Q mate a s e t d r m. h group o s s o th alkali metalsand said X 0 comprising the titratable.

alkalinity of said borate-hypochlorite composition.

2. A composition of matter consisting essentially of a stableborate-hypochlorite bleach in a solid substantially.

dry form, said borate-hypochlor-ite having from 0.15 to one materialselected from the group consisting of the alkali metals and said X 0comprising the titratable alkalinity of said borate-hypochloritecomposition.

3. A composition of matter consisting essentially of a stable sodiumborate-hypoohlorite bleach in a solid substantially dry form, saidsodium borate-hypochlorite having from 0.029 to 0.36 mole of (OCl-) permole of B 0 and from 0.30 to 0.90 mole of Na O per mole of B 0 said Na Ocomprising the titratable alkalinity of said sodium borate-hypochloritecomposition.

4. The composition of matter of claim 3 wherein the (OCl-) B 0 moleratio is from 0.15 to 0.2 and the Na O B 0 mole ratio is from 0.30 to0.60.

5. The method of making a stable alkali metal boratehypochlorite bleachin a solid substantially dry form which comprises making an aqueoussolution of caustic 'soda," chlorinating said caustic soda solution,slurrying into said chlorinated caustic soda solution at least onematerial selected from the class consisting of the alkali metal boratesand boric acid and rapidly drying said slurry, said ingredients added insuch proportion that the resultant product has from 0.029 to 0.36 moleof 001-) per mole of B 0 and from 0.30 to 0.90 mole of X 0 per mole of B0 where X is a material selected from the group consisting of the alkalimetals, and X 0 comprises the titratable alkalinity of said alkali metalborate-hypochlorite bleach.

6. The method of making a stable alkali metal boratehypochlorite bleachin a solid substantially dry form which comprises chlorinating anadmixture consisting essentially of at least one material selected fromthe group consisting of the alkali metal borates and boric acid and atleast one material selected from the group consisting of sodiumhydroxide and potassium hydroxide and rapidly drying said chlorinatedmass, said ingredients added in such proportion that the resultantproduct has from 0.029 to 0.36 mole of (001-) per mole of B 0 and from0.30 to 0.90 mole of (OCl'-) per mole of B 0 wherein X is a materialselected from the group consisting of the alkali metals and said X 0comprises the titratable alkalinity of said alkali metal-hypochloritebleach.

7. The method of making a stable sodium borate-hypochlorite bleach in asolid substantially dry form which comprises making an aqueous causticsoda solution, chlorinating said aqueous caustic soda solution,slurrying into said chlorinated caustic soda solution at least onematerial selected from the group consisting of the sodium borates andboric acid and rapidly drying said slurry, said ingredients added insuch proportion that the resultant product has from 0.15 to 0.20 mole of(001-) per mole of B 0 and from 0.30 to 0.60 mole of Na O per mole of B0 said Na O comprising the titratable alkalinity'of said sodiumborate-hypochlorite bleach.

8. The method of making a stable sodium borate-hypochlorite bleach in asolid substantially dry form which comprises chlorinating an admixtureconsisting essentially of sodium hydroxide and at least one materialselected from the group consisting of the sodium borates and boric acidand rapidly drying said chlorinated mass, said ingredients added in suchproportion that the resultant product has from 0.15 to 0.20 mole of(001-) per mole of B 0 and from 0.30 to 0.60 mole of Na O per mole of B0 said Na O comprising the titratable alkalinity of said sodiumborate-hydrochlorite.

References Cited in the file of this patent UNITED STATES PATENTS

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A STABLEBORATE-HYPOCHLORITE BLEACH IN A SOLID SUBSTANTIALLY DRY FORM, SAIDBORATE-HYPOCHLORITE HAVING FROM 0.029 TO 0.36 MOLE OF (OC1-) PER MOLE OFB2O3 AND FROM 0.30 TO 0.90 MOLE OF X2O PER MOLE OF B2O3, WHERE X IS ATLEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF THE ALKALIMETALS AND SAID X2O COMPRISING THE TITRATABLE ALKALINITY OF SAIDBORATE-HYPOCHLORITE COMPOSITION.